var engine = LinearOptimizationService.createEngine();
// Create a linear constraint with the bounds 0 and 10
var constraint = engine.addConstraint(0, 10);
// Create a variable so we can add it to the constraint
engine.addVariable('x', 0, 5);
// Set the coefficient of the variable in the constraint. The constraint is now:
// 0 <= 2 * x <= 5
constraint.setCoefficient('x', 2);